Chapter 1. Admin Guide

1.1. Overview

User location module. The module keeps a user location table and
provides access to the table to other modules. The module exports no
functions that could be used directly from scripts.

1.1.1. Contact matching

How the contacts are matched (dor same AOR - Address of Record) is an
important aspect of the usrloc modules, especialy in the context of NAT
traversal - this raise mre problems since contacts from different
phones of same users may overlap (if behind NATs with same
configuration) or the re-register contact of same phone may be
seen as a new one (due different binding via NAT).

The SIP RFC 3261 publishes a matching algorithm based only on the
contact string with callid and cseq number extra checking (if callid
is the same, it must have a higher cseq number, otherwise invalid).
But as argumented above, this is not enough in NAT traversal context,
so the OpenSIPS implementation of contact machting offers more algorithms:

contact based only - it strict RFC 3261
compiancy - the contact is matched as string and extra checked
via callid and cseg (if callid is the same, it must have a
higher cseq number, otherwise invalid).

contact nad callid based - it an extension
of the first case - the contact and callid must matched as
string; the cseg must be higher than the previous one - so be
careful how you deal with REGISTER retransmissions in this
case.

1.3.20. db_mode (integer)

The usrloc module can utilize database for persistent contact storage.
If you use database, your contacts will survive machine restarts or
SW crashes. The disadvantage is that accessing database can be very
time consuming. Therefore, usrloc module implements four database
accessing modes:

0 - This disables database completely. Only memory will be used.
Contacts will not survive restart. Use this value if you need a
really fast usrloc and contact persistence is not necessary or
is provided by other means.

1 - Write-Through scheme. All changes to usrloc are immediately
reflected in database too. This is very slow, but very reliable.
Use this scheme if speed is not your priority but need to make
sure that no registered contacts will be lost during crash or
reboot.

2 - Write-Back scheme. This is a combination of previous two
schemes. All changes are made to memory and database
synchronization is done in the timer. The timer deletes all
expired contacts and flushes all modified or new contacts to
database. Use this scheme if you encounter high-load peaks
and want them to process as fast as possible. The mode will
not help at all if the load is high all the time. Also, latency
of this mode is much lower than latency of mode 1, but slightly
higher than latency of mode 0.

3 - DB-Only scheme. No memory cache is kept, all operations being
directly performed with the database. The timer deletes all
expired contacts from database - cleans after clients that didn't
un-register or re-register. The mode is useful if you configure
more servers sharing the same DB without any replication at SIP
level. The mode may be slower due the high number of DB operation.
For example NAT pinging is a killer since during each ping cycle
all nated contact are loaded from the DB; The lack of memory
caching also disable the statistics exports.

Warning

In case of crash or restart contacts that are in memory only and
haven't been flushed yet will get lost. If you want minimize the
risk, use shorter timer interval.

1.3.22. cseq_delay (integer)

Delay (in seconds) for accepting as retransmissions register requests
with same Call-ID and Cseq. The delay is calculated starting from the
receiving time of the first register with that Call-ID and Cseq.

Retransmissions within this delay interval will be accepted and replied
as the original request, but no update will be done in location. If the
delay is exceeded, error is reported.

A value of 0 disable the retransmission detection.

Default value is “20 seconds”.

Example 1.22. Set cseq_delay parameter

...
modparam("usrloc", "cseq_delay", 5)
...

1.3.23. fetch_rows (integer)

The number of the rows to be fetched at once from database
when loading the location records. This value can be used
to tune the load time at startup. For 1MB of private memory (default)
it should be below 4000. The database driver must support
fetch_result() capability.

Default value is “2000”.

Example 1.23. Set fetch_rows parameter

...
modparam("usrloc", "fetch_rows", 3000)
...

1.3.24. hash_size (integer)

The number of entries of the hash table used by usrloc to store the
location records is 2^hash_size. For hash_size=4, the number of entries
of the hash table is 16.

Default value is “9”.

Example 1.24. Set hash_size parameter

...
modparam("usrloc", "hash_size", 10)
...

1.4. Exported Functions

There are no exported functions that could be used in scripts.

1.5. Exported MI Functions

1.5.1.
ul_rm

Deletes an entire AOR record (including its contacts).

Parameters:

table name - table where the AOR
is removed from (Ex: location).

AOR - user AOR in username[@domain]
format (domain must be supplied only if use_domain option
is on).

1.5.2.
ul_rm_contact

Deletes a contact from an AOR record.

Parameters:

table name - table where the AOR
is removed from (Ex: location).

AOR - user AOR in username[@domain]
format (domain must be supplied only if use_domain option
is on).

contact - exact contact to be removed

1.5.3.
ul_dump

Dumps the entire content of the USRLOC in memory cache

Parameters:

brief - (optional, may not be present); if
equals to string “brief”, a brief dump will be
done (only AOR and contacts, with no other details)

1.5.4.
ul_flush

Triggers the flush of USRLOC memory cache into DB.

1.5.5.
ul_add

Adds a new contact for an user AOR.

Parameters:

table name - table where the contact
will be added (Ex: location).

AOR - user AOR in username[@domain]
format (domain must be supplied only if use_domain option
is on).

contact - contact string to be added

expires - expires value of the contact

Q - Q value of the contact

unused - unused attribute (kept for
backword compatibility)

flags - internal USRLOC flags of the
contact

cflags - per branch flags of the
contact

methods - mask with supported requests
of the contact

1.5.6.
ul_show_contact

Dumps the contacts of an user AOR.

Parameters:

table name - table where the AOR
resides (Ex: location).

AOR - user AOR in username[@domain]
format (domain must be supplied only if use_domain option
is on).

1.6. Exported statistics

Exported statistics are listed in the next sections.

1.6.1. users

Number of AOR existing in the USRLOC memory cache for that domain
- can not be resetted; this statistic will be register for each
used domain (Ex: location).

1.6.2. contacts

Number of contacts existing in the USRLOC memory cache for that
domain - can not be resetted; this statistic will be register for
each used domain (Ex: location).

1.6.3. expires

Total number of expired contacts for that domain - can be resetted;
this statistic will be register for each used domain
(Ex: location).

1.6.4. registered_users

Total number of AOR existing in the USRLOC memory cache for all
domains - can not be resetted.

Chapter 2. Developer Guide

2.1. Available Functions

2.1.1.
ul_register_domain(name)

The function registers a new domain. Domain is just another name for
table used in registrar. The function is called from fixups in
registrar. It gets name of the domain as a parameter and returns
pointer to a new domain structure. The fixup than 'fixes' the
parameter in registrar so that it will pass the pointer instead of the
name every time save() or lookup() is called. Some usrloc functions
get the pointer as parameter when called. For more details see
implementation of save function in registrar.

Meaning of the parameters is as follows:

const char* name - Name of the domain
(also called table) to be registered.

2.1.2.
ul_insert_urecord(domain, aor, rec)

The function creates a new record structure and inserts it in the
specified domain. The record is structure that contains all the
contacts for belonging to the specified username.

Meaning of the parameters is as follows:

udomain_t* domain - Pointer to domain
returned by ul_register_udomain.

str* aor - Address of Record (aka
username) of the new record (at this time the record will
contain no contacts yet).

urecord_t** rec - The newly created
record structure.

2.1.3.
ul_delete_urecord(domain, aor)

The function deletes all the contacts bound with the given Address
Of Record.

Meaning of the parameters is as follows:

udomain_t* domain - Pointer to domain
returned by ul_register_udomain.

str* aor - Address of record (aka
username) of the record, that should be deleted.

2.1.4.
ul_get_urecord(domain, aor)

The function returns pointer to record with given Address of Record.

Meaning of the parameters is as follows:

udomain_t* domain - Pointer to domain
returned by ul_register_udomain.

str* aor - Address of Record of request
record.

2.1.5.
ul_lock_udomain(domain)

The function lock the specified domain, it means, that no other
processes will be able to access during the time. This prevents race
conditions. Scope of the lock is the specified domain, that means,
that multiple domain can be accessed simultaneously, they don't block
each other.

Meaning of the parameters is as follows:

udomain_t* domain - Domain to be locked.

2.1.6.
ul_unlock_udomain(domain)

Unlock the specified domain previously locked by ul_lock_udomain.

Meaning of the parameters is as follows:

udomain_t* domain - Domain to be
unlocked.

2.1.7.
ul_release_urecord(record)

Do some sanity checks - if all contacts have been removed, delete
the entire record structure.

The function inserts a new contact in the given record with
specified parameters.

Meaning of the parameters is as follows:

urecord_t* record - Record in which
the contact should be inserted.

str* contact - Contact URI.

time_t expires - Expires of the
contact in absolute value.

float q - q value of the contact.

str* callid - Call-ID of the REGISTER
message that contained the contact.

int cseq - CSeq of the REGISTER
message that contained the contact.

unsigned int flags - Flags to be set.

ucontact_t* cont - Pointer to newly
created structure.

str* ua - User-Agent of the REGISTER
message that contained the contact.

struct socket_info *sock - socket on
which the REGISTER message was received on.

2.1.9.
ul_delete_ucontact
(record, contact)

The function deletes given contact from record.

Meaning of the parameters is as follows:

urecord_t* record - Record from which
the contact should be removed.

ucontact_t* contact - Contact to be
deleted.

2.1.10.
ul_get_ucontact(record, contact)

The function tries to find contact with given Contact URI and
returns pointer to structure representing the contact.

Meaning of the parameters is as follows:

urecord_t* record - Record to be
searched for the contact.

str_t* contact - URI of the request
contact.

2.1.11.
ul_get_all_ucontacts
(buf, len, flags)

The function retrieves all contacts of all registered users and
returns them in the caller-supplied buffer. If the buffer is too small,
the function returns positive value indicating how much additional
space would be necessary to accommodate all of them. Please note
that the positive return value should be used only as a
“hint”, as there is no guarantee that during the time
between two subsequent calls number of registered contacts will
remain the same.

If flag parameter is set to non-zero value then only contacts that
have the specified flags set will be returned. It is, for example,
possible to list only contacts that are behind NAT.